Ricin-type beta-trefoil lectin domain.

lectin. Lectins are important adhesin proteins, which bind carbohydrate structures on host cell surface. The carbohydrate specificity of diverse lectins to a large extent dictates bacteria tissue tropism by mediating specific attachment to unique host sites expressing the corresponding carbohydrate receptor.

Ricin-type beta-trefoil; Carbohydrate-binding domain formed from presumed gene triplication. The domain is found in a variety of molecules serving diverse functions such as enzymatic activity, inhibitory toxicity and signal transduction. Highly specific ligand binding occurs on exposed surfaces of the compact domain sturcture.

Ricin-type beta-trefoil. Carbohydrate-binding domain formed from presumed gene triplication.

glycosyl hydrolase family 16. The O-Glycosyl hydrolases are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A glycosyl hydrolase classification system based on sequence similarity has led to the definition of more than 95 different families inlcuding glycosyl hydrolase family 16. Family 16 includes lichenase, xyloglucan endotransglycosylase (XET), beta-agarase, kappa-carrageenase, endo-beta-1,3-glucanase, endo-beta-1,3-1,4-glucanase, and endo-beta-galactosidase, all of which have a conserved jelly roll fold with a deep active site channel harboring the catalytic residues.